1. Field of the Invention
This invention relates to knives used in enlarging the incision used in laparoscopic surgery.
2. Description of Related Art
The major disorder associated with the gallbladder is the presence of gallstones. The usual treatment for gallstones is surgical removal.
Endoscopic or laparoscopic devices enable surgeons to perform various surgical procedures within body cavities under endoscopic observation and without requiring large surgical incisions. Such procedures are typically done by inserting an endoscope and necessary instruments through one or more openings or incisions of 1 cm or less in length which penetrate a body wall. The process of removing a gall bladder, referred to as a laparoscopic cholecystectomy, begins with the insertion of a hollow needle into the abdominal cavity. A gas, such as carbon dioxide, is injected to create a work place in the abdominal cavity. A trocar having an outer cannula and an inner blade is used to penetrate the abdominal wall and enter the abdominal cavity. The inserted cannula is sometimes referred to as a trocar port.
The inner blade of the trocar is withdrawn leaving the cannula through which various instruments are inserted for the manipulation and detachment of the gall bladder. The gall bladder is drawn to the cannula and withdrawn from the abdominal cavity through the cannula. It is desirable to withdraw the intact gall bladder. This is accomplished by drawing the intact, detached gall bladder to the inner opening of the cannula and then withdrawing the cannula and attached gall bladder from the incision in the abdominal wall. In some cases, however, the diameter of the cannula and of the incision is too small for the gall bladder with the gall stones to traverse the abdominal wall. Such an oversized gall bladder may rupture or be broken by the surgeon, necessitating the laborious and time consuming removal of gall bladder stones from the abdominal cavity.
The incision knife of the present invention is used to enlarge the incision when an oversized gall bladder with stones presents. This incision knife is guided by the cannula by a hemispheric guide which also serves as a shield which prevents inadvertent damage to the gall bladder. The enlarged incision allows the desirable removal of an intact gall bladder, despite its large stones.
Use of an ordinary surgeon's knife or scalpel to enlarge an endoscopic incision is not acceptable because of the hazard of making an incision of uncontrolled length and of the hazard of damaging the gall bladder.
U.S. Pat. No. 5,263,937 discloses a safety trocar which requires reduced force to penetrate the abdominal wall. The trocar has a blade with a shoulder and a shaft. The shaft is inserted in a cannula which approximates the diameter of the shoulder and finger-like segments which smooth the transition between blade and cannula and reduce the force required to penetrate the abdominal wall.
U.S. Pat. No. 5,273,024 discloses instruments for endoscopic surgical procedures for treatment of transverse carpal ligaments. A cannula having a longitudinal groove is used to penetrate the carpal tunnel. A knife is then inserted into and oriented by the groove and used to cut the ligament.
SU 1181640 discloses a medical gouge with a handle, grip, blade, screws, gutter, and bar. The gutter has a curved surface encompassing approximately 1/4 of a circle and is attached approximately at a right angle to the blade. The edges of the gutter are sharp-pointed. The gouge is used for multi-plane osteotomy of the body of the os ilium.
None of the prior art knives achieve the purpose of the present invention, that of enlarging a laparoscopic incision allowing the passage of an intact gall bladder.